Wood Lemming
Encyclopedia
The Wood Lemming is a species of rodent
in the family Cricetidae
. It belongs into the Arvicolinae
subfamily of rodent
s therefore is a relative of the vole
s, lemming
s, and muskrat
s.
It is found in the taiga biome of China
, Finland
, Mongolia
, Norway
, Russia
, and Sweden
.
s, the normal X and a mutated X*. Females with that mutation on their X*-chromosome inhibit the male determining effect of the Y chromosome. This leads three genetic types of females XX, X*X and X*Y and one genetic type of males XY. The X*X and X*Y females are fertile but only produce XX* ova, which means they only produce female offspring. Its not fully known the extent to which nature balances out the differences in the adult population, but sampling studies seem to suggest that males do make up as little as 25% of the population at equilibrium. Females with abnormal genotype (XO, XXY, XYY) occur regularly. The high female sex ratio may be an adaptation against local mate competition and inbreeding during population low points.
If geographical features do not allow the animals to disperse evenly during their migration, then thousands of lemmings can be seen on their migration. This migratory behavior was exaggerated in popular stories about lemmings that in innumerable numbers dash down the hillsides and fall down over rocks into the sea, only to drown. However, such stories of mass suicides in lemmings are mere legends.
The size of home range between male and female wood lemmings varies greatly. Male home ranges (>2000m2) are 5 to 7 times larger than those of females.
, Polytrichum
, Ptilium, and Pleurozium, with Dicranum being the moss of choice. It was found that in Northern Finland, Dicranum spp. made up the majority of the lemming’s winter food supply. It is thought that these mosses are preferred because of their usability and relatively high nitrogen content. Lemmings will also eat some grass species such as Deschampsia
, as well as the leaves and stems of Vaccinium
spp.
to Kamchatka
(taiga area of Eurasia). The ideal habitat for the wood lemming is a spruce forest with thick, copious moss cover. Lemmings gravitate towards areas that have abundant areas of cover from predators i.e. holes provided by decomposed trees, stumps, and mossy rock. In the winter, wood lemmings seek out drier areas than summer.
. Compared to other vole
s, lemmings drink greater amounts of water, which may be why they seek moister areas in the spring and summer. As far as average distances traveled by lemmings, males travel distances anywhere from 4-12 times longer than females.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
. It belongs into the Arvicolinae
Arvicolinae
The Arvicolinae are a subfamily of rodents that includes the voles, lemmings, and muskrats. They are most closely related to the other subfamilies in the Cricetidae . Some authorities place the subfamily Arvicolinae in the family Muridae along with all other members of the superfamily Muroidea...
subfamily of rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s therefore is a relative of the vole
Vole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...
s, lemming
Lemming
Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. They are subniveal animals, and together with voles and muskrats, they make up the subfamily Arvicolinae , which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes rats,...
s, and muskrat
Muskrat
The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...
s.
It is found in the taiga biome of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, and Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
.
Sex determination
Wood Lemmings produce about 3 times as many females as male offspring. This is due to an unusual genetic system where they have two different types of X chromosomeChromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s, the normal X and a mutated X*. Females with that mutation on their X*-chromosome inhibit the male determining effect of the Y chromosome. This leads three genetic types of females XX, X*X and X*Y and one genetic type of males XY. The X*X and X*Y females are fertile but only produce XX* ova, which means they only produce female offspring. Its not fully known the extent to which nature balances out the differences in the adult population, but sampling studies seem to suggest that males do make up as little as 25% of the population at equilibrium. Females with abnormal genotype (XO, XXY, XYY) occur regularly. The high female sex ratio may be an adaptation against local mate competition and inbreeding during population low points.
Population Dynamics
The population density of lemmings shows extreme peaks interspersed by years of very low densities. In peak years wood lemmings migrate from overpopulated areas to areas of low population density. The migration usually begins around the end of July and end in early October. The migratory distances are typically quite short, ranging a few kilometers at most, with no specific direction.If geographical features do not allow the animals to disperse evenly during their migration, then thousands of lemmings can be seen on their migration. This migratory behavior was exaggerated in popular stories about lemmings that in innumerable numbers dash down the hillsides and fall down over rocks into the sea, only to drown. However, such stories of mass suicides in lemmings are mere legends.
The size of home range between male and female wood lemmings varies greatly. Male home ranges (>2000m2) are 5 to 7 times larger than those of females.
Diet
The diet of the wood lemming consists mostly of moss. The most commonly consumed species of moss are DicranumDicranum
Dicranum is a genus of mosses, also called Wind-Blown Mosses or Fork Mosses.These mosses form in densely packed clumps. Stems may fork, but do not branch. In general, upright stems will be single but packed together. These are commonly found in Jack pine or Red pine stands....
, Polytrichum
Polytrichum
Polytrichum is a genus of mosses — commonly called haircap moss or hair moss — which contains approximately 70 species that cover a cosmopolitan distribution....
, Ptilium, and Pleurozium, with Dicranum being the moss of choice. It was found that in Northern Finland, Dicranum spp. made up the majority of the lemming’s winter food supply. It is thought that these mosses are preferred because of their usability and relatively high nitrogen content. Lemmings will also eat some grass species such as Deschampsia
Deschampsia
Deschampsia is a genus of grasses in the family Poaceae, commonly known as hair grass or tussock grass. There are 30 to 40 species....
, as well as the leaves and stems of Vaccinium
Vaccinium
Vaccinium is a genus of shrubs or dwarf shrubs in the plant Family Ericaceae. The fruit of many species are eaten by humans and some are of commercial importance, including the cranberry, blueberry, bilberry or whortleberry, lingonberry or cowberry, and huckleberry...
spp.
Habitat
Wood Lemmings can be found in areas from southern NorwayNorway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
to Kamchatka
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
(taiga area of Eurasia). The ideal habitat for the wood lemming is a spruce forest with thick, copious moss cover. Lemmings gravitate towards areas that have abundant areas of cover from predators i.e. holes provided by decomposed trees, stumps, and mossy rock. In the winter, wood lemmings seek out drier areas than summer.
Metabolism
The wood lemming is well adapted to live in cold climates due to its high thermogenic capacity, thermal insulation, and non-shivering thermogenesisThermogenesis
Thermogenesis is the process of heat production in organisms. It occurs mostly in warm-blooded animals, but a few species of thermogenic plants exist.-Types:...
. Compared to other vole
Vole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...
s, lemmings drink greater amounts of water, which may be why they seek moister areas in the spring and summer. As far as average distances traveled by lemmings, males travel distances anywhere from 4-12 times longer than females.